Texas Instruments Corporation

Raytheon Company

Carlos A Castro

Luigi Colombo

Malcolm John Bevan

Donald F Weirauch

Sebastian R Borrello

Herbert F Schaake

Magid Yousri Dimyan

Ralph Korenstein

Kent R Carson

This is a sensor for, and a method of, determining if a particular type of flame is present, using at least two uncooled HgCdTe detector films on a common IR transmissive substrate. Specific examples of the types of radiation which can be identified include gasoline flames, natural gas flames, and organic combustion flames (identified, e.g., by comparing the amount of combined carbon dioxide and carbon monoxide to the amount of water vapor). The ratio of carbon dioxide to carbon monoxide can also be determined. The sensor can include a first HgCdTe filter (88) on a common IR transmissive substrate (42), a first uncooled HgCdTe detector film (86) over the first filter (88), and a second uncooled HgCdTe detector film (92) on a CdTe insulator which is either on the first uncooled HgCdTe detector film, or on a second HgCdTe filter (94) provided on the common IR transmissive substrate.

Uncooled infrared sensors for the detection and identification of

An epitaxial layer of a narrow-gap semiconductor is deposited on a substrate comprising a wider-gap semiconductor. The opposite surface of the substrate is then illuminated with light pulses at a wavelength corresponding to the desired bandgap of the resulting material. Each pulse causes localized heating where it first encounters a material having a sufficiently narrow bandgap to be an absorber at the wavelength of illumination. This localized heating will then cause interdiffusion, producing a layer of semiconductor alloy having a bandgap intermediate between the bandgaps of the two starting materials. Repetition of this step will have the effect of moving the region of localized absorption away from the original location, and toward the film/air interface. Since the desired end product composition will be transparent to the illumination applied, the process is inherently self-limiting. By appropriately selecting the wavelength of illumination applied, variously proportioned semiconductor compositions may be obtained, so that the bandgap of the resulting material may be arbitrarily selected to have any desired value between the bandgaps of the two starting materials. No surface damage is caused by this technique.

Process for forming semiconductor alloys having a desired bandgap

A HgCdTe film is produced on a CdTe substrate, by depositing HgTe on a CdTe substrate, and then illuminating the substrate from the underside with infrared light at a wavelength longer than the desired operating wavelength (band-gap-equivalent wavelength) of the device. Since CdTe is transparent in the infrared, the light will reach the HgTe/CdTe interface. Since HgTe is an absorber in the infrared, most of the infrared radiation will be absorbed near the interface, which will cause intense localized heating and thus accelerate the interdiffusion of HgTe and CdTe. This interdiffusion will have the effect of moving the interface away from the original location, and toward the film/air interface. Since the desired end-product HgCdTe composition will be transparent to the infrared radiation applied, the process is inherently self-limiting. By appropriately selecting the infrared wavelength applied, variously proportioned HgCdTe compositions may be obtained, so that the effective band gap of the device can be selected at will. Moreover, no surface damage is caused by this technique.

Process for forming HgCoTe alloys selectively by IR illumination

In a non-volatile random access memory, a selected one of a plurality of magnetic cells arranged in an array on a major surface of a substrate is inductively switched between opposite remanent, i.e. permanent, states upon the simultaneous application of electrical pulses to a pair of conductors intersecting adjacent the selected cell, each of the electrical pulses having an amplitude less than, but the sum thereof being at least equal to, the amplitude required to inductively switch the remanent state of the selected cell.

Magnetic domain random access memory

A method for fabricating a magnetic memory film is disclosed wherein an epitaxial layer of magnetizable material is grown on the surface of a substrate which has been selectively implanted to damage portions of the crystalline surface. The resulting polycrystalline portion of the epitaxial layer grown on the damaged substrate surface is then selectively removed to leave the monocrystalline portions of the epitaxial layer.

Growing community of inventors

Garland, TX, United States of America

Carlos A Castro